An apparatus for generating electrical power downhole comprises a housing located in a drillstring. A primary flow channel is formed through the housing. At least two secondary flow channels are located in the housing and arc laterally displaced from the primary flow channel, A fluid driven electrical generator is positioned in each of the at least two secondary flow channels. A controllable flow diverter is associated with each of the secondary flow channels to controllably divert at least a portion of a fluid flow m the primary flow channel to at least one of the at least two secondary flow channels to drive the generator therein.
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13. An apparatus for generating electrical power downhole comprising:
a housing located in a drillstring;
a primary flow channel through the housing;
at least one secondary flow channels in the housing, the at least one secondary flow channel laterally displaced from the primary flow channel;
a first fluid driven electrical generator positioned in the primary flow channel;
at least one second fluid driven electrical generator positioned in the at least one secondary flow channel; and
a controllable flow diverter to controllably apportion the fluid flow to the primary flow channel and the at least one secondary flow channel to drive the generators therein.
7. A method of generating electrical energy downhole comprising;
positioning a housing located in a drillstring;
forming a primary flow channel through the housing;
forming at least two secondary flow channels in the housing, the at least two secondary flow channels laterally displaced from the primary flow channel;
positioning a first fluid driven electrical generator positioned within the primary flow channel;
positioning at least one second fluid driven electrical generator in each of the at least two secondary flow channels; and
using at least one controllable flow diverter to controllably apportion fluid flow to the primary flow channel and to at least one of the at least two secondary flow channels to drive the second fluid driven electrical generator therein.
1. An apparatus for generating electrical power downhole comprising:
a housing located in a drillstring;
a primary flow channel through the housing;
at least two secondary flow channels in the housing, the at least two secondary flow channels laterally displaced from the primary flow channel;
a first fluid driven electrical generator positioned within the primary flow channel;
at least one second fluid driven electrical generator positioned in each of the at least two secondary flow channels; and
at least one controllable flow diverter associated with each of the secondary flow channels, the at least one controllable flow diverter being operable to controllably apportion a fluid flow to the primary flow channel and to at least one of the at least two secondary flow channels to drive the generator therein.
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The present disclosure relates generally to the field of drilling wells and more particularly to downhole power generation.
Electrical power for use in the downhole drilling environment may be supplied by batteries in the downhole equipment, or by downhole fluid driven generators. Downhole batteries may suffer reliability problems at high temperatures. Fluid driven generators may be required to operate over a wide range of flow rates. As the flow rate increases, mechanical loads on the generator components increase, possibly causing mechanical failures. Electrical generators typically continue to generate more power as the rotational rate increases. At high flow rates, this high power output may generate more power than is necessary for the intended application. The excess power generation may lead to excessive heat generation both in the generator, and in the power conversion and conditioning electronics.
During drilling operations a suitable drilling fluid (also referred to in the art as “mud”) 131 from a mud pit 132 is circulated under pressure through drill string 120 by a mud pump 134. Drilling fluid 131 passes from mud pump 134 into drill string 120 via fluid line 138 and kelly joint 121. Drilling fluid 131 is discharged at the borehole bottom 151 through an, opening in drill bit 150. Drilling fluid 131 circulates uphole through the annular space 127 between drill string 120 and borehole 126 and is discharged into mud pit 132 via a return line 135. Preferably, a variety of sensors (not shown) are appropriately deployed on the surface according to known methods in the art to provide information about various drilling-related parameters, such as fluid flow rate, weight on bit, hook load, etc.
In one example embodiment of the present disclosure, a bottom hole assembly (BHA) 159 may comprise a measurement while drilling (MWD) system 158 comprising various sensors to provide information about the formation 123 and downhole drilling parameters. BHA 159 may be coupled between the drill bit 150 and the drill pipe 122.
MWD sensors in BHA 159 may include, but are not limited to, a sensors for measuring the formation resistivity near the drill bit, a gamma ray instrument for measuring the formation gamma ray intensity, attitude sensors for determining the inclination and azimuth of the drill string, and pressure sensors for measuring drilling fluid pressure downhole. The above-noted sensors may transmit data to a downhole telemetry transmitter 133, which in turn transmits the data uphole to the surface control unit 140. In one embodiment a mud pulse telemetry technique may be used to communicate data from downhole sensors and devices during drilling operations. A transducer 143 placed in the mud supply line 138 detects the mud pulses responsive to the data transmitted by the downhole transmitter 133. Transducer 143 generates electrical signals in response to the mud pressure variations and transmits such signals to a surface control unit 140. Surface control unit 140 may receive signals from downhole sensors and devices via sensor 143 placed in fluid line 138, and processes such signals according to programmed instructions stored in a memory, or other data storage unit, in data communication with surface control unit 140. Surface control unit 140 may display desired drilling parameters and other information on a display/monitor 142 which may be used by an operator to control the drilling operations. Surface control unit 140 may contain a computer, a memory for storing data, a data recorder, and other peripherals. Surface control unit 140 may also have drilling, log interpretation, and directional models stored therein and may process data according to programmed instructions, and respond to user commands entered through a suitable input device, such as a keyboard (not shown).
In other embodiments, other telemetry techniques such as electromagnetic and/or acoustic techniques, or any other suitable technique known in the art may be utilized for the purposes of this invention. In one embodiment, hard-wired drill pipe may be used to communicate between the surface and downhole devices. In one example, combinations of the techniques described may be used. In one embodiment, a surface transmitter receiver 180 communicates with downhole tools using any of the transmission techniques described, for example a mud pulse telemetry technique. This may enable two-way communication between surface control unit 140 and the downhole tools described below.
In one embodiment, a downhole electrical generator system 190 may be located in BHA 159 for generating electrical power for use by various downhole tools and/or sensors. Downhole power generation may be problematic for a number of reasons. For example, downhole power generation can be affected by downhole temperature and the drilling shock and vibration environment. Downhole fluid driven electrical generators may be adversely affected by variations in the fluid flow rate that are dictated by the drilling plan and/or changes in the drilling plan. For example, a fluid driven generator system may be sized to produce a given power output at a relatively low flow rate for a given drilling section. A fluid driven generator typically turns faster and puts out more power as flow increases. Higher flow may impose higher rotational rate resulting in higher loads and wear on the rotating members. In addition, there may be additional frictional heat generated internal to the generator that has a detrimental effect. Further, the additional power may overload associated downhole power control circuitry, causing costly downhole failures.
In the example shown, each secondary flow channel 201 A,B has a controllable flow diverter assembly 208 A,B associated therewith. Each controllable flow diverter assembly 208 A,B may be individually actuated to controllably divert at least a portion 131 A,B of fluid flow 131 through secondary channels 201 A,B respectively, to cause a related amount of power to be generated by each fluid driven generator 220 A,B. As shown, controllable flow diverter assemblies 208 A,B may each comprise a gate 211 A,B that may be controllably positioned in opening 200 A,B between primary flow channel 204 and each secondary flow channel 201 A,B, by a controllable actuator 210 A,B. Controllable actuators 210 A,B are each operably coupled to a downhole controller 260, described below. Controllable actuators 210 A, B may comprise an electrical actuator, for example a solenoid or a linear motor. Alternatively, a hydraulic piston may be used. In one example each controllable actuator 210 A,B may be independently actuated to allow fluid flows 131A,B in the respective secondary flow channels, 201 A,B. In one example, fluid flow may be allowed through one of the secondary flow channels 201A,B, with the other secondary flow channel closed to through flow. The “A” generator may be considered a primary generator and the “B” generator may be considered a backup. If the “A” generator exhibits reduced output, or other failure, the “B” generator may be used to extend the drilling time without removing the drillstring from the wellbore. In another example, fluid flow 131 A,B may be simultaneously diverted through the respective secondary flow channels to provide for an increased downhole fluid flow rate. Flow through the flow channels may be controlled according to programmed instructions in controller 260, described below.
In another embodiment, see
In yet another embodiment, see
Flow channel 404 has at least two pivotable segments 414 A,B positioned around the internal periphery of primary flow passage 404. Pivotable segments 414 A,B may be controllably actuated by actuator assemblies 408 A,B to pivot inwards to constrict fluid flow in primary flow channel 404. The constriction diverts flow through secondary flow channels 401A,B. The amount of constriction is controllable. When the primary flow channel is constricted, fluid flow portions 431 A,B cause generators 220 A,B to generate electrical power. The amount of power generated by generators 220 A,B may be controlled by controlling, the amount of constriction of primary flow channel 404. The amount of constriction is regulated by actuator assemblies 408 A,B comprising actuators 410 A,B, and linkage members 413 A,B. Actuators 410 A,B each have a linearly extendable shaft 411 A,B, respectively. Controllable actuators 410A,B may comprise an electrical actuator, for example a solenoid or a linear motor. Alternatively, a hydraulic piston may be used. Linkage members 413 A,B are coupled between actuator shaft 411 A,B and pivotable segments 414 A,B respectively. Linear motion of actuator shafts 411 A,B causes the pivotable segments 414 A,B to pivot into primary flow channel 404 to constrict primary flow 431. In one example, actuators 410 A,B are operatively coupled to controller 260 by electrical and/or optical couplers (not shown) run thorough wiring passages in housing 405. Such wiring techniques are known on the art and are not described here in detail. In operation, flow may be diverted to secondary flow channels 401 A,B for power generation at low flow rates. At higher flow rates, the diverter may be opened allowing fluid to flow through primary flow channel.
Flow through the flow channels of the various example embodiments may be controlled by downhole controller 260. In one example, controller 260 acts according to programmed instructions to detect at least one parameter of interest of each of the generators and to actuate each of the flow diverters based on the at least one parameter of interest.
Carroll, Sean, Downing, Andrew
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jun 05 2013 | CARROLL, SEAN | Halliburton Energy Services, Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 046121 | /0418 | |
Jun 07 2013 | DOWNING, ANDREW | Halliburton Energy Services, Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 046121 | /0418 | |
Jun 17 2013 | Halliburton Energy Services, Inc. | (assignment on the face of the patent) | / |
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